Endohedral fullerenes containing Gd atoms are a promising new class of compounds with the potential to be superior MRI contrast agents. Fullerenes are a newly discovered class of hollow, closed shell, all carbon molecules that can hold single or multiple lanthanide atoms such as gadolinium inside their shell. Such compounds have a number of important advantages as contrast agents in imaging applications. Unlike conventional compounds, the trapped lanthanide is complete protected from the outside environment, and therefore will not be released into the body. In addition, the compounds show very high relaxivities, on the order of five times higher than current imaging agents. As a result, they are ideal in applications where the imaging agent is to be retaining in the body for a long period of time. This project will improve the methods for extracting and purifying the Gd-metallofullerenes, develop improved methods of making the compounds water soluble, and measure the water solubility, relaxivity and stability of the resulting derivitized compounds. The best compounds will be further tested to determine their toxicity, elimination pathways, in vivo distributions and half lives, and their performance in actual MRI imaging experiments. PROPOSED COMMERCIAL APPLICATIONS: This research will lead to the development of an entirely new class of lanthanide fullerene compounds that have potential applications not only in improving contrast in magnetic resonance imaging, but in scintillation imaging, PET imaging and SPECT imaging. This class of compounds could also have applications to the delivery of radio-pharmaceuticals.